Re: Migratory Cover doubles as bottom
The migratory cover does have a couple good uses such as a quick bottom board. However most people don't use them that way as it leaves NO space for the bees to cluster at the bottom of the hive. When you set a hive body onto a bottom board you have about 3/4 of an inch there where the bees can cluster as well as room to go in and out of the hive easily. When you set a standard hive body on a migratory cover (even if it does have an entrance opening) there is only about 1/8 of an inch there where the bees can move through, which means they won't, and have to migrate through the hive by climbing over frames, etc.
Now the other side of this is, if you plan to use an upper entrance above the frames, this can be a cheap easy method of bottom boards. They are just plywood 3/4 inch with cleats on the bottom sides, about 3/4 by 1.5 inches. The migratory covers usually cover over the box side to side and that's it, from front to back give an extra 3/4 inch for bee escapes and ease of use. Other then that there's not much more to them.
Thomas B - Since 2013, 10 - 8 F langs, Italian currently, TF + Oils